input[type=color] should look like a button

- We should apply ButtonFace background instead of white.
- For fallback style, use |1px #a9a9a solid| border to match Aura buttons.
- Adjust paddings

BUG=360997
TEST=automated

Review URL: https://codereview.chromium.org/225413019

git-svn-id: svn://svn.chromium.org/blink/trunk@171032 bbb929c8-8fbe-4397-9dbb-9b2b20218538